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<p>Microbialite deposits in thermal spring environments represent integrated biogeological archives formed through interactions among microbial communities, mineral precipitation, and hydrological conditions. In semi-arid regions of central Mexico, many thermal springs have undergone recent desiccation; however, the ecological and geochemical signals preserved within exposed microbialite deposits remain poorly documented. In this study, microbialite facies and associated epilithic diatom assemblages were investigated in four thermal springs of the La Playa system (Guanajuato, Mexico) using a multiproxy approach integrating microbialite morphology, diatom community structure, mineralogical composition, bulk geochemistry, and stable carbon and oxygen isotopes. Three microbialite facies—stromatolitic, thrombolitic, and dendrolitic—were identified, displaying distinct structural characteristics associated with differences in water availability and depositional conditions. Diatom assemblages were characterized by the dominance of <i>Stephanocyclus</i> sp. and <i>Denticula valida</i>, whereas other taxa occurred at comparatively lower relative abundances. Variability in taxon richness, dominance, and community composition among springs reflects spatial differences in hydrological conditions. Stable carbon (<i>δ</i><sup>13</sup>C) and oxygen (<i>δ</i><sup>18</sup>O) isotope values provide an additional geochemical line of evidence consistent with hydrological variability across the spring system and reflect the influence of evaporation, hydrochemical conditions, and CO<sub>2</sub> degassing on carbonate precipitation. The convergence of microbialite facies characteristics, diatom assemblage composition, and stable isotope signatures indicates that microbialite deposits from the La Playa thermal springs preserve evidence of hydrological and ecological heterogeneity within a desiccated hydrothermal system. This study highlights the value of a multiproxy framework for interpreting environmental variability in thermal spring settings and underscores the role of microbialites as natural archives in fragile hydrothermal environments.</p>

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Diatom assemblages and microbialite facies as multiproxy records of hydrological variability in the La Playa thermal springs, Guanajuato, Mexico

  • 期刊论文

  • 发表日期：

    2026年8月3日

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  • María Jesús Puy-Alquiza,
  • Berenice Noriega Luna,
  • Yuriko Jocselin Martínez Hernández,
  • Raúl Miranda-Avilés,
  • Alberto Sánchez Gonzalez,
  • Miren Yosune Miranda Puy,
  • Cristina Daniela Moncada Sanchez

摘要

Microbialite deposits in thermal spring environments represent integrated biogeological archives formed through interactions among microbial communities, mineral precipitation, and hydrological conditions. In semi-arid regions of central Mexico, many thermal springs have undergone recent desiccation; however, the ecological and geochemical signals preserved within exposed microbialite deposits remain poorly documented. In this study, microbialite facies and associated epilithic diatom assemblages were investigated in four thermal springs of the La Playa system (Guanajuato, Mexico) using a multiproxy approach integrating microbialite morphology, diatom community structure, mineralogical composition, bulk geochemistry, and stable carbon and oxygen isotopes. Three microbialite facies—stromatolitic, thrombolitic, and dendrolitic—were identified, displaying distinct structural characteristics associated with differences in water availability and depositional conditions. Diatom assemblages were characterized by the dominance of Stephanocyclus sp. and Denticula valida, whereas other taxa occurred at comparatively lower relative abundances. Variability in taxon richness, dominance, and community composition among springs reflects spatial differences in hydrological conditions. Stable carbon (δ13C) and oxygen (δ18O) isotope values provide an additional geochemical line of evidence consistent with hydrological variability across the spring system and reflect the influence of evaporation, hydrochemical conditions, and CO2 degassing on carbonate precipitation. The convergence of microbialite facies characteristics, diatom assemblage composition, and stable isotope signatures indicates that microbialite deposits from the La Playa thermal springs preserve evidence of hydrological and ecological heterogeneity within a desiccated hydrothermal system. This study highlights the value of a multiproxy framework for interpreting environmental variability in thermal spring settings and underscores the role of microbialites as natural archives in fragile hydrothermal environments.